High-discrimination antenna array for capacitance-responsive circuits

ABSTRACT

A multi-element antenna array for use with capacitanceresponsive circuits to enable discrimination between human occupants and animals or packages resting on an automobile seat.

United States Patent [1 1 Atkins HIGH-DISCRIMINATION ANTENNA ARRAY FOR CAPACITANCE-RESPONSIVE CIRCUITS [75] Inventor: Carl E. Atkins, Montclair, NJ.

[73] Assignee: Wagner Electric Corporation,

Newark, NJ.

[22] Filed: Apr. 20, 1972 [21] Appl. No.: 245,799

[52] US. Cl. 307/10 SB, 340/278, 340/258 C [51] Int. Cl 02g 3/00 [58] Field of Search 307/10 R, 10 SB;

317/246; ZOO/DIG. 1; 340/278, 258 C [56] References Cited I UNITED STATES PATENTS 3,439,358 4/1969 Salmons 340/278 UX June 19, 1973 3,449,714 6/1969 Farley 307/10 SB 3,177,967 4/1965 Wilson v H 307/10 S11 3,194,975 7/1965 Diamond .1 200/D1(1. 1

Primary Examiner-Robert K. Schaefer Assistant Examin erM. Ginsburg Attorn ey-william D. Lucas [57] ABSTRACT A multi-element antenna array for use with capacitance-responsive circuits to enable discrimination between human occupants and animals or packages resting on an automobile seat.

10 Claims, 1 Drawing Figure HIGH-DISCRIMINATION ANTENNA ARRAY FOR CAPACITANCE-RESPONSIVE CIRCUITS CROSS-REFERENCES TO RELATED APPLICATIONS The present invention may be advantageously employed with the circuits disclosed in copending U. S. Pat. application Ser. No. 263,182 entitled CAPACI- TANCE-RESPONSIVE CONTROL CIRCUIT filed on June 15, 1972 in the name of Carl E. Atkins, and in copending U. S. Pat. application Ser. No. 280,219 entitled CAPACITANCE-RESPONSIVE CONTROL CIR- CUIT filed on Aug. 14, 1972 in the name ofCarl E. Atkins.

BACKGROUND OF THE INVENTION As a safety measure, it has been found desirable to incorporate in automotive vehicles a system which will give a warning and/or prevent operation of the vehicle if one or more of the human occupants has not fastened his seat belt after entering the vehicle. However, priorart systems have encountered the problem of discriminating between packages or animals resting on a seat and a human occupant, who may range from a small child to a full-grown adult. Systems employing a pressure-sensitive switchvplaced under the seat are incapable of such discrimination, since those switches are actuated by weight alone. A large package or a large dog may weigh as much as a small child, and could therefore actuate the system when it should not be actuated.

SUMMARY OF THE INVENTION The present invention is embodied in and carried out by a multi-element antenna array for use in conjunction with a capacitance-responsive system to discriminate between humans and animals or inanimate objects which may occupy a seat as in, for example, an automobile.

BRIEF DESCRIPTION OF THE DRAWING The present invention will be better understood when the written description thereof is read with reference to the accompanying drawing, which illustrates applicants novel antenna array installed in a seat, along with the coupling circuitry connecting the array to the associated capacitance-responsive circuit.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawing, a seat such as may be found in an automotive vehicle is shown as the environment of use of applicants multi-element antenna array. A first electrically-conductive element 12 in the form of a plate or a thin, flexible foil or coating is disposed on or near a surface of the back-rest portion of the seat, and is coupled to the associated capacitanceresponsive circuit by a capacitance 14 which may be fixed, as shown, or variable. A second electrically conductive element 16, also in the form ofa plate or a thin, flexible foil or coating, is disposed on a surface of the fundament-supporting portion of the seat 10, and is coupled to the associated capacitance-responsive circuit by a capacitance 18 which also may be fixed, as shown, or variable. A third electrically conductive element 20 in the form of a wire or a flexible rod is disposed along at least the forward edge of the fundamentsupporting portion of the seat 10, and is coupled to the associated capacitance-responsive circuit by a resistance 22, which may be fixed, as shown, or variable.

By employing a multi-element array of the type just described, it is possible to discriminate between human seat occupants and various animals or objects which may rest on the seat. This result is achieved by virtue of the fact that only a human occupant will capacitively couple to all three antenna elements l2, l6 and 20 simultaneously and to the degree required to cuase the capacitance-responsive circuit to alter its output. If an object is placed on the seat 10, it may closely couple to element 16, or to elements 12 and 16, depending on its size and orientation, but it will not closely couple to all three elements simultaneously. Similarly, if an animal such as a dog or a cat is occupying the seat 10, it may closely couple only to element 16, or possibly to elements l2 and 16, but again, it will not closely couple to all three elements. Also, the degree of capacitive coupling by an animal or an object to any'element, particularly element 20, is not likely to be as close as the coupling effected by a human occupant. Thus, the coupling by animals or objects to specific elements of the antenna array may be less close than by humans, but still effective, or not close at all and therefore ineffective. The cumulative effect of such reduced close coupling and ineffective coupling is to leave the output of the capacitance-responsive circuit unaltered. Consequently, it will be appreciated that the high degree of discrimination achieved by applicants antenna array is a function of both l the inability of animals or objects to closely couple to all three elements simultaneously and (2) the inability of animals or objects to couple as closely as a human occupant to those elements to which effective coupling is made.

The circuitry interconnecting the various antenna elements to the capacitance-responsive circuit is designed to alter the sensitivity of each element with respect to the other elements. For example, in the preferred embodiment shown in the drawing, the area elements l2 and 16 are de-sensitized to a degree by their respective capacitors 14 and 18. On the other hand, the linear element 20 is made relatively more sensitive in terms of its effect on the capacitance-responsive circuit by its connection thereto through resistance 22. Since element 20 will most probably be effectively coupled only by human seat occupants, it is desirable that coupling with this element have a greater effect on the capacitance-responsive circuit than would coupling with other elements 12 and 16. Resistor 22, which is optionally included, is of a relatively low value, e.g., a few hundred ohms. It may be eliminated and element 20 may be connected directly to the capacitanceresponsive circuit. Similarly, elements 12 and 16 may be directly coupled to the capacitance-responsive circuit, with the weighted effect of coupling with these elements being controlled by varying the area of the elements. Alternatively, if in certain applications it is desired to make either elements 12 or 16 more sensitive, the associated coupling capacitance may be either reduced in value, or eliminated, or replaced by a resistance.

The antenna array disclosed herein may be employed with a wide variety of capacitance-responsive circuits which are known or may become known in the art. For example, the capacitance formed by the antenna array, or by the antenna array in combination with its coupling circuitry, may be the only capacitive element in a circuit, or it may be connected in series or in parallel with one or more other capacitances, which may be fixed or variable.

The advantages of the present invention, as well as certain changes and modifications of the disclosed embodiment thereof, will be readily apparent to those skilled in the art. It is the applicants intention to cover all those changes and modifications which could be made to the embodiment of the invention herein chosen for the purposes of the disclosure without departing from the spirit and scope of the invention.

What is claimed is:

1. In a system including capacitance-responsive circuit, the improvement comprising: multi-element antenna means coupled to said capacitance-responsive circuit to enable discrimination by said capitanceresponsive circuit between (a) humans and (b) animals or objects the size or shape of which is substantially different from humans by the degree of capacitive coupling to each element of said antenna means when positioned in the vicinity of said antenna means.

2. The improvement according to claim 1 wherein said multi-element antenna means comprises:

1. a first electrically conductive element disposed over a first predetermined area;

2. a second electrically conductive element disposed over a second predetermined area; and

3. a third electrically conductive element disposed along a predetermined line.-

3. The improvement according to claim 2 wherein said first electrically conductive element is disposed in the region of the back-rest portion of a seat, said second electrically conductive element is disposed in the region of the fundament-supporting portion of said seat, and said third electrically conductive element is disposed'along at least a segment of the forward edge of the fundament-supporting portion of said seat.

4. The improvement according to claim 2 further comprising first, second and third coupling circuit means associated with said first, second and third electrically conductive elements, respectively, each coupling circuit meansbeing operative to modify the effect upon the capacitance-responsive circuit of capacitive coupling by humans, animals or objects to the elements associated with said coupling circuit means.

I 5'. The improvement according to claim 4 wherein said first coupling circuit means comprises a first capacitance, said second coupling circuit means comprises a second capacitance, and said third coupling circuit means comprises a resistance.

6. In a system including a seat having a back-rest portion and a fundament-supporting portion and a capacitance-responsive circuit, the improvement comprising: multi-element antenna means disposed in predetermined regions of said back-rest and fundamentsupporting portions of said seat and coupled to said capacitance-responsive circuit to enable discrimination by said capacitance-responsive circuit between (a) humans and (b) animals or objects the size or shape of which is substantially different from humans by the degree of capacitive coupling to each element of said antenna means when occupying said seat.

7. The improvement according to claim 6 wherein said multi-element antenna means comprises:

1. a first electrically conductive element disposed in the region of said back-rest portion of said seat;

2. a second electrically conductive element disposed in the region of said fundament-supporting portion of said seat; and

3. a third electrically conductive element disposed along at least a segment of the forward edge of said fundament-supporting portion of said seat.

8. The improvement according to claim 7 wherein said first electrically conductive element is disposed over a first predetermined area, said second electrically conductive element is disposed over a second predetermined area, and said third electrically conductive element is disposed along a'predetermined line.

9. The improvement according to claim 7 further comprising first, second and third, coupling circuit means associated with said first, second and third electrically conductive elements, respectively, each coupling circuit means being operative to modify the effect upon the capacitance-responsive circuit of capacitive coupling by humans, animals and objects to the elements associated with said coupling circuit means.

10. The improvement according to claim 9 wherein said first coupling circuit means comprises a first capacitance, said second coupling circuit means comprises a second capacitance, and said third coupling circuit means comprises a resistance. 

1. In a system including capacitance-responsive circuit, the improvement comprising: multi-element antenna means coupled to said capacitance-responsive circuit to enable discrimination by said capitance-responsive circuit between (a) humans and (b) animals or objects the size or shape of which is substantially different from humans by the degree of capacitive coupling to each element of said antenna means when positioned in the vicinity of said antenna means.
 2. The improvement according to claim 1 wherein said multi-element antenna means comprises:
 2. a second electrically conductive element disposed over a second predetermined area; and
 2. a second electrically conductive element disposed in the region of said fundament-supporting portion of said seat; and
 3. a third electrically conductive element disposed along a predetermined line.
 3. a third electrically conductive element disposed along at least a segment of the forward edge of said fundament-supporting portion of said seat.
 3. The improvement according to claim 2 wherein said first electrically conductive element is disposed in the region of the back-rest portion of a seat, said second electrically conductive element is disposed in the region of the fundament-supporting portion of said seat, and said third electrically conductive element is disposed along at least a segment of the forward edge of the fundament-supporting portion of said seat.
 4. The improvement according to claim 2 further comprising first, second and third coupling circuit means associated with said first, second and third electrically conductive elements, respectively, each coupling circuit means being operative to modify the effect upon the capacitance-responsive circuit of capacitive coupling by humans, animals or objects to the elements associated with said coupling circuit means.
 5. The improvement according to claim 4 wherein said first coupling circuit means comprises a first capacitance, said second coupling circuit means comprises a second capacitance, and said third coupling circuit means comprises a resistance.
 6. In a system including a seat having a back-rest portion and a fundament-supporting portion and a capacitance-responsive circuit, the improvement comprising: multi-element antenna means disposed in predetermined regions of said back-rest and fundament-supporting portions of said seat and coupled to said capacitance-responsive circuit to enable discrimination by said capacitance-responsive circuit between (a) humans and (b) animals or objects the size or shape of which is substantially different from humans by the degree of capacitive coupling to each element of said antenna means when occupying said seat.
 7. The improvement according to claim 6 wherein said multi-element antenna means comprises:
 8. The improvement according to claim 7 wherein said first electrically conductive element is disposed over a first predetermined area, said second electrically conductive element is disposed over a second predetermined area, and said third electrically conductive element is disposed along a predetermined line.
 9. The improvement according to claim 7 further comprising first, second and third coupling circuit means associated with said first, second and third electrically conductive elements, respectively, each coupling circuit means being operative to modify the effect upon the capacitance-responsive circuit of capacitive coupling by humans, animals and objects to the elements associated with said coupling circuit means.
 10. The improvement according to claim 9 wherein said first coupling circuit means comprises a first capacitance, said second coupling circuit means comprises a second capacitance, and said third coupling circuit means comprises a resistance. 